According to a new study, firstborn girls face a much higher risk of being overweight than their younger siblings.
“This is the fourth study we have done to characterize the health risks of firstborn in four different populations. If you look at the health risks of those that are firstborn, you find that firstborns are more insulin resistant than later borns, which is a risk factor for diabetes, and they have higher blood pressure than later borns,” said lead study author Dr. Wayne Cutfield, who is a professor of pediatric endocrinology working at the Liggins Institute of the University of Auckland, New Zealand.
Even if the study is purely observational, it does show that women have a 29 percent higher risk of being overweight and up to 40 percent increased chance of being obese if they were born first in the family. Moreover, the numbers also showed they were a bit taller than their younger sisters.
The findings of this study also match other similar studies that prove firstborn men are more likely to be fatter than their brothers.
In order to reach such conclusions, the researchers looked at the data of about 27,000 women who were born between 1973 and 1988. This data included more than 13,000 sister pairs.
An explanation for the higher risk of obesity a firstborn girl faces might be the less amount of blood that reaches the placenta during a woman’s first pregnancy compared to later pregnancies. This is due to the narrower blood vessels. Moreover, it is assumed that less nutrients reach the firstborn, which is why they usually tend to weigh less at the beginning.
Due to the fact that the study is observational, a cause-and- effect between weight and birth order cannot be established, but the research is definitely a starting point for further research.
In addition to that, it provides useful information to families who want to protect their children from the obesity epidemic. It is important to note that being a firstborn exposes you more and you should make better lifestyle choices and take preventive measures. Thus, you can chose to have a healthy diet and exercise as much as possible.
The results of the study were published in the online Journal of Epidemiology and Community Health on Wednesday, August 26.
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